Appearing on The AM Show on Friday, Ms Collins said it was "unfortunate for the Prime Minister Jacinda Ardern to go charging in like she did and try and embarrass the Australians".

"This is a very complex issue, and there's more information coming out that's making it look even more complex. There's more information today out in the media around some of the people who are on this island."

Ms Collins didn't elaborate on what she's heard. It could be unconfirmed reports in Australian media that some of the asylum seekers have been luring underage girls into rented rooms in Lorengau, a small town on Manus Island, for sex.

"They've gone through a UN process now, but they certainly haven't had the sort of screening that New Zealand normally expects. We just want to be a little bit careful, see what else comes out."

She said Ms Ardern needed to "learn from Winston Peters that you actually do have to be a little bit more statesman-like when you're overseas and representing New Zealand".

"It's not student politics time. This is where she's going to have to step up a bit."